1. Field of the Invention
The present invention is generally directed to telephones. In particular, the present invention is related to telephones capable of communicating over a data network.
2. Background Art
A recent trend in devices connected to a data communications network is to make such devices discoverable on the network, have them expose network services, and allow other nodes on the network to request these services. Protocols such as Universal Plug and Play (UPnP™), Jini™, and Salutation™ provide mechanisms for one device to discover the presence of a particular device (or class of device) on the network and invoke services upon it. Another related protocol, Rendezvous™ (networking technology offered by Apple Computer Inc. of Cupertino, Calif.), provides a way for services to register themselves and be discovered, although the actual protocol for service invocation must be known to both communicating parties.
Many network devices use a subset of these discovery protocols to support the use of low-level “automatic configuration” protocols. Both UPnP™ and Apple's Rendezvous™, for example, support a “zero configuration” (zeroconf) protocol known as AutoIP to assign Internet Protocol (IP) addresses even if a Dynamic Host Configuration Protocol (DHCP) server is not present.
A device that implements UPnP™ can configure itself on the network, broadcast an announcement of its existence, allow UPnP™ control points (other nodes) to query its functional interface, allow others to access a web site that it is hosting, and allow others to invoke functions on that device. A UPnP™ control point can receive announcements of UPnP™ devices on the network, can query for devices of a particular type or with particular attributes, can query an individual device for its interface, and can invoke functions on that device.